For years, the sharp curves and poorly marked intersections of Sunset Boulevard from UCLA to the sea have lured speeders with disastrous results, including the loss of four young lives during the past year.

Michael Stafford, a civil engineer who oversees Westside street improvements for the city of Los Angeles, thinks he has found a partial solution: left-turn lanes and realignment of curves at nine intersections in Pacific Palisades and Brentwood.

"The thing about Sunset Boulevard is it's a real classic example of the laws of physics," Stafford said. "When you violate the laws of physics, you're rarely forgiven.

"What I'm trying to do is provide some forgiveness there, banking curves, improving sight distances, giving people a safe place to turn left from."

But Alexander Man, co-chairman of a citizens' group concerned about the future of Sunset, says the city's plans are going to cause more problems without significantly improving safety.

He believes the street widening required for each of the projects will add up to more traffic, more noise and more pollution and perhaps even more accidents in the affluent, ordered neighborhoods that border the boulevard.

And so the two sides are facing off.

Man's Committee for a Safe and Scenic Sunset and several local homeowners' associations are calling on the city to study the cumulative impact of all nine projects before beginning any construction. Committee representatives testified Tuesday before the Environmental Quality Board, a panel that advises the planning department.

"We believe the impact will be massive," Man told the board.

The board will consider at its Oct. 22 meeting whether to request a cumulative environmental impact report for the Sunset projects.

Stafford opposes the idea.

"We accumulated some projects over the years and all of a sudden they say, 'Hey, you got a traffic corridor here,' " he said.

"Technically, they're right. But is it worth waiting to do needed projects so you can write about the whole thing at once?"

The contract on the first project--a left-turn lane at Sunset and Allenford Avenue that would broaden the street there from 50 feet to 63 feet--has already gone out to bid, and construction is to begin this year, Stafford said.

Environmental studies were not required on the Allenford project because it is not a major construction effort and few trees will be removed, Stafford said.

The next project planned is a left-turn median and the banking of a curve at Evans Road, an intersection that police call "Deadman's Curve."

Stafford wants to start construction there in 1986. A study of the impacts of all nine projects could delay the work at Evans by two years, Stafford said. "How do I write about how projects will affect the environment when I haven't designed them yet?" he asked.

Construction is scheduled to have started on the last of the projects by 1988, Stafford said. The construction costs for all nine would top $4 million.

If they are completed, Man said, the effect will be to allow Sunset to handle more traffic than it does now. He said he worries that the boulevard will become a major artery, attracting cars bound for the airport or the beach.

He pointed out that the Brentwood-Pacific Palisades District Plan, adopted by the City Council in 1977, prohibits widening of Sunset "for the purpose of increasing capacity" until 1997.

Said Stafford: "From a traffic engineering point of view, the only way you can increase capacity is to add more through lanes, not more left-turn lanes."

To the residents near Sunset, however, street widening is street widening.

"My house is going to be right on the street if they widen it. My front door will be six feet from the sidewalk," said Walter Adams, who has lived in the Palisades for 16 years. "Already, coming out of the driveway you have to wait and wait."

The city's plans are "overkill," said Kenneth Schaefler, who represented the Homeowners Assn. of Rustic Canyon at the environmental board meeting.

"We want traffic control. We want lights, we want police monitoring.

"But widening the streets will just bring more speeders and more accidents. I have a little kid. We're frightened."

The city wants to widen these Sunset Boulevard intersections to add left-turn lanes: